A method for isolation of hundreds of milligrams of lolitrem B is reported. Lolitrem E, the most abundant of the minor lolitrems, was isolated from side fractions and its structure determined by mass spectrometry and one- and two-dimensional NMR techniques. Lolitrem E differs from lolitrem B in being an ether, rather than an acetal, derivative of lolitriol. Evidence is presented that the compound previously isolated by Gallagher and co-workers, and assigned the structure of lolitrem C, was in fact lolitrem E. Lolitrem E, which is not tremorgenic in mice, is proposed as a biosynthetic precursor of lolitrem B.